The present disclosure relates to an aluminum bronze alloy and a method for producing an aluminum bronze alloy. The present disclosure further relates to a product made of such an aluminum bronze alloy.
Numerous requirements are imposed on alloys for friction applications, such as those for piston sleeves or axial bearings of a turbocharger. A suitable alloy should have a low coefficient of friction in order to minimize the power loss resulting from friction, and to reduce the generation of heat in the area of frictional contact. In addition, it should be taken into consideration that for typical applications, the friction partners are present in a lubricated environment, and in principle, good adhesion of the lubricant to the alloy is desired. Moreover, during contact with the lubricant under friction load, a stable tribological layer should form which, like the underlying base matrix of the alloy, has a high thermal stability and good heat conductivity. Furthermore, a wide-ranging oil tolerance is desirable so that the alloy and the tribological layers are largely insensitive to changes in the lubricant.
Another objective is to provide an alloy having a high mechanical load capacity, and a sufficiently high 0.2% yield strength in order to minimize plastic deformations under load. In addition, a high tensile strength and hardness should be present in order for the alloy to withstand abrasive and adhesive loads. Furthermore, the dynamic load capacity should be high enough to ensure robustness against impact stresses. Furthermore, a preferably high fracture toughness retards the crack growth rate, starting from microdefects; with regard to defect growth, the alloy is preferably free of residual stresses.
In many cases, suitable alloys for parts under friction load are special brasses, which in addition to copper and zinc as the primary components are alloyed with at least one of the elements nickel, iron, manganese, aluminum, silicon, titanium, or chromium. Silicon brasses in particular meet the requirements stated above; CuZn31Si1 represents a standard alloy for friction applications such as piston sleeves.
Furthermore, it is known to use tin bronzes, which in addition to tin and copper additionally contain nickel, zinc, iron, and manganese, for friction applications or also for mining applications. Another alloy class for parts under friction load is the aluminum bronzes, which in addition to copper and aluminum may contain alloy additives selected from the group comprising nickel, iron, manganese, aluminum, silicon, tin, and zinc. For faster-moving components under friction load, when aluminum bronzes are used, the additional advantage of weight reduction is achieved due to the lightweight element aluminum. With regard to parts under friction load made of brass or red brass, the parts made from the previously known aluminum bronzes are suitable only for relatively slow-moving friction components.
Use of a copper-aluminum alloy having a cover layer of aluminum oxide for use as a bearing material for manufacturing a sliding bearing is known from DE 101 59 949 C1. The cited document discloses an aluminum proportion of 0.01 to 20%, as well as the use of further optional elements from the group comprising iron, cobalt, manganese, nickel, silicon, and tin up to a maximum 20% total, as well as optionally up to 45% zinc. Additional wide-ranging alloy compositions for silicon bronze are described in U.S. Pat. No. 6,699,337 B2, JP 04221033 A, DE 22 39 467 A, and JP 10298678 A.
The foregoing examples of the related art and limitations therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.